The present invention relates to a vehicle drive device provided with an input member drivingly connected to an internal combustion engine, a rotary electric machine, a speed change mechanism drivingly connected to the rotary electric machine, an output member drivingly connected to the speed change mechanism and wheels, and an engagement device that is capable of changing the state of engagement between the input member and the speed change mechanism.
Description of the Related Art
As conventional techniques of a vehicle drive device such as described above, there are techniques described in, for example, Japanese Patent Application Publication No. 2011-105192 (JP 2011-105192 A) and Japanese Patent Application Publication No. 2010-196867 (JP 2010-196867 A). Note that, in the description of this Description of the Related Art section, names of relevant members in JP 2011-105192 A and JP 2010-196867 A will be cited in square brackets. In a structure described in JP 2011-105192 A, hydraulic pressure supplied from an electric pump [electric pump 7] is controlled and fed to an engagement device [clutch device 3] arranged between an input member [input shaft 32] and an rotary electric machine [electric motor 1] in a power transmission path, and thus, the state of engagement of the engagement device is changed. Here, the electric pump is a hydraulic pump driven by an rotary electric machine dedicated to hydraulic control separately from the rotary electric machine [electric motor 1] serving as a source of vehicle driving force.
With such a structure, the discharge performance of the pump could be insufficient if a small-sized pump is used as the electric pump in order to improve mountability of the vehicle drive device to the vehicle. Although it is conceivable to cover the insufficiency in the discharge performance by increasing the number or diameter of friction plates, increasing the number or diameter of the friction plates could lead to an increase in size of the engagement device. Therefore, downsizing of the vehicle drive device has its own limits.
JP 2010-196867 A describes a structure in which a hydraulic unit [first clutch hydraulic unit 6] that controls hydraulic pressure supplied to an engagement device [first clutch CL1] is provided in a hydraulic pressure control device [AT hydraulic pressure control valve unit CVU] that controls hydraulic pressure supplied from a mechanical pump [mechanical pump OP]. Here, the mechanical pump is a hydraulic pump driven by a source of vehicle driving force. With such a structure, the discharge performance of the pump is more easily ensured than with the structure of JP 2011-105192 A. Therefore, there is less necessity of the countermeasure of covering the insufficiency in the discharge performance of the pump by increasing the number or diameter of the friction plates. However, with the structure described in JP 2010-196867 A, the distance from the hydraulic unit to a servo oil chamber [hydraulic pressure chamber 53] of the engagement device is likely to be long, and thus, the engagement device could deteriorate in response and controllability.